Offspring are rarely identical to their parents - HSC - SSCE Biology - Question 25 - 2022 - Paper 1

Genetic variation can arise through different mechanisms in asexual and sexual reproduction.

Asexual Reproduction

In asexual reproduction, offspring are produced by a single organism through processes such as mitosis. This can lead to genetic variation primarily through:

• Mutations: Random changes in DNA during replication can introduce new traits into the population.
• Environmental Factors: Changes in environmental conditions may affect some individuals differently, leading to a variation in characteristics over generations.

Sexual Reproduction

In sexual reproduction, genetic variation arises through:

• Meiosis: The process of meiosis involves the reduction of chromosome numbers by half and the shuffling of alleles through crossing-over and independent assortment. This means that each gamete (sperm or egg) carries different combinations of genetic material.
• Fertilization: The random combination of gametes during fertilization introduces variation, as each offspring inherits different alleles from both parents.

Key Differences

1. Source of Variation: Asexual reproduction relies on mutations as its main source of variation, while sexual reproduction combines genetic material from two parents, leading to a higher potential for diversity.
2. Process Involved: Asexual reproduction mainly involves mitosis, whereas sexual reproduction involves meiosis, which introduces recombination and assortment of genes.
3. Outcomes: As a result, sexual reproduction typically leads to offspring that are more genetically diverse compared to those produced via asexual reproduction.